1980 Alternator out-put

Closed Thread Subscribe

Thread Tools

Search this Thread

Feb 23, 2021 | 12:55 PM

Kdeman1

Thread Starter

Racer

Joined: Sep 2014

Posts: 421

Likes: 34

From: Troy Michigan

1980 Alternator out-put

1980 Alternator out-putting 15.3V, this seems a bit high... I just purchased a new battery and don't want to fry the thing....

I also tried replacing the voltage regulator on the alternator but still it appears to output high.

Question to all those smarter than I, should i consider replacing the alternator to receive the coveted 14.5V, or am I okay... and just on the high side of the charging spec.

Best,
Kevin

Feb 23, 2021 | 01:06 PM

lakerider57

Racer

Joined: Jul 2007

Posts: 397

Likes: 77

From: Jasper, GA

Seems high to me, I normally see around 13.8v - 14.3v output from alternator. Are you sure your new battery is good ?
Sometimes the alternator will over-charge if the battery isn't good.

Richard

Feb 23, 2021 | 01:15 PM

Kdeman1

Thread Starter

Racer

Joined: Sep 2014

Posts: 421

Likes: 34

From: Troy Michigan

Quote:

Originally Posted by lakerider57

Seems high to me, I normally see around 13.8v - 14.3v output from alternator. Are you sure your new battery is good ?
Sometimes the alternator will over-charge if the battery isn't good.

Richard

I believe so, my alternator was charging the old around the same voltage... I assumed this was due to it being old and at the end of the day was bad due to low cracking amps...
I have a repair manual I’ll give it a read and post what I find

Feb 23, 2021 | 01:41 PM

lakerider57

Racer

Joined: Jul 2007

Posts: 397

Likes: 77

From: Jasper, GA

Are you measuring the charging voltage at the alternator or at the battery ? Are they the same in your case ?

just trying to understand,
Richard

Feb 23, 2021 | 01:53 PM

Kdeman1

Thread Starter

Racer

Joined: Sep 2014

Posts: 421

Likes: 34

From: Troy Michigan

15.3 volts at the battery,

15.5 measured at the alt,

14.8 measured between terminal 2 and ground.

based on the manual it recommends a overhaul...

Feb 23, 2021 | 05:14 PM

Kdeman1

Thread Starter

Racer

Joined: Sep 2014

Posts: 421

Likes: 34

From: Troy Michigan

Well I took it apart and ran all the recommended checks and everything looked okay... I am unable to check the regulator without a special tool... so I might replace that component.

tbd

Feb 26, 2021 | 12:18 AM

7T1vette

Team Owner

Joined: Jan 2006

Posts: 37,637

Likes: 3,118

From: Crossville TN

Is the alternator a 1-wire replacement alt or similar to the stock 2-wire system? If it is a 2-wire alt, you may have the wires in the connector reversed (or the leads internally reversed from the rebuilder). If so, the alt will be 'tricked' into running at max output.

Dec 27, 2023 | 10:15 AM

dr914

Racer

Joined: Oct 2013

Posts: 438

Likes: 221

From: Marietta Georgia

I just read this without looking at any of the other comments on purpose. first the leaking battery is a dead giveaway of overcharging (make sure that you spray baking soda and water mix in the area to neutralize any invisible acid that has spilled) Overcharging is always caused by a defective voltage regulator. The fact that you are getting so much charge makes it certain that the alternator is putting out, the voltage is just not being regulated by the regulator. (this of course assumes that there is not some kind of wiring short!!!)